1000 Sudoku Books For Adults Hard Jumbo Collection of Sudoku Books for Adults. Find on every page in this book that will challenge you to solve each puzzle, Sudoku puzzles are a proven method for enhancing logic skills. As a logic puzzle, Sudoku is also a great brain game. If you play Sudoku every day, you'll soon begin to see improvements within your concentration and overall brain power. You could reduce your probabilities of Dementia or Alzheimer's simply by solving Sudoku puzzles. By using this selection of sudoku puzzle books you would experience enhanced brain capabilities for example focus, logical thinking, and memory.1000 Sudoku Books for adults hard.difficultySudoku puzzles grid size in the book is 9x9 that is played with nine number 1,2,3,4,5,6,7,8,9 An answer key for each sudoku puzzle Puzzles are printed on high-quality white paper, paper size 8,5 x 11 inchesSimple instructions for beginnersGreat for grandad, grandma, dad, and mom Buy Now!Choose your book today by clicking on the "Add to Cart" button at the top of this page.